A wide range of medical implants are known from the prior art. In conjunction with the present invention, an electromedical implant is understood to be an active implant, which, besides a power supply (for example, a battery), also comprises further electrical and/or electronic components (for example, capacitors), which are arranged in a housing that is hermetically sealed. Electromedical implants of this type include, for example, cardiac pacemakers, defibrillators or neurostimulators. These implants are used to excite the biological tissue by means of electrical pulses, which are generated by a pulse generator provided in the housing.
Implants of this type are often connected to electrode lines, which, after implantation in a body, are used to treat said body, for example, to transmit and/or deliver stimulation pulses and/or defibrillator shocks to specific points of the body, or are used to detect electric potentials of points of the body. To this end, an electrical connection has to be produced between the electrical and/or electronic components arranged inside the housing and the electrode line. This electrical connection is generally produced by means of a bushing, and what is known as a terminal housing. Here, a bushing ensures an electrical connection between the interior of the housing and the external environment, and is responsible at the same time for the hermetic seal of the housing. The terminal housing fastened via the bushing further guides the electrical connection of the bushing to a contact point, which is often formed as a plug contact socket. The connector piece (e.g., plug) of the electrode line is introduced after implantation into the generally standardized plug contact socket. Electrical contact is thus produced at the contact points of the plug contact socket between the electronic components of the implant, for example, a pulse generator, and the contact points of the connector piece of the electrode line and, therefore, of the electrode fastened thereto.
The interface between the implant and the electrode line is normally designed as a detachable multipoint connection and is defined in terms of its geometry via ISO standards. A coaxially stepped, double pug connection with sealing lips is defined in Standard ISO 5841-3 (IS-1 Standard) for pulse generators with cardiac pacemaker function, that is to say for pulse generators that operate with low-voltage pulses. A coaxially stepped, quadruple plug connection (of which three are in-line and smooth) with sealing lip systems integrated in the socket opening is defined in Standard ISO 27186 (DF4/IS4 Standard) for pulse generators with cardiac pacemaker function and/or defibrillator function, that is to say with high-voltage and low-voltage pulses. By contrast, there are no standard guidelines for a plug/socket geometry of neurostimulators. In products known at the time of filing of the present application, plug/socket systems with eight coaxial-smooth plug connections with sealing lip systems integrated into the socket opening are used, for example.
In the mentioned plug systems, all contactings can be formed in principle via spring contacts, provided specific demands in terms of the plug-in force, retention force and pull-out force, and also the electrical contact stability, are met.
In the known plug contact sockets, the sealing lip systems in life-sustaining implants (cardiac pacemakers, defibrillators, etc.) are normally designed redundantly, that is to say sealing lip pairs are used on either side of the individual electrical contact regions in order to keep bodily fluid away from the contact point, and also to electrically insulate the contact points from one another. In the case of implants that are not life-sustaining (for example, neurostimulators), a deviation is made from this rule.
From document International Publication No. WO 2006/026186, an implant with a plug contact socket for a multipoint plug connection is known, which has a plurality of electrically conductive, toroidal contact springs (spring coils). Here, each spring coil is arranged in a corresponding metal spring ring in such a way that the spring coil surrounds the outer periphery of the opening for the introduction of the plug at the respective point. Furthermore, on each spring ring, a wire feed line fastened thereto is provided and produces the electrical contact with the interior of the implant housing. The unit formed from a spring coil, the associated spring ring and the wire feed line fastened thereto is also referred to as a spring contact component. Together with the plastic housing likewise disclosed in the above document, a contact socket component is formed.
In other known solutions, the spring ring is omitted and the toroidal contact spring is mounted in a spring cage made of electrically conductive material. Here, the spring cage is often produced as a metal form-milled part. The contact socket component is assembled manually from the spring coil and spring cage. In a further manual method step, plug contact sockets are produced by stringing together contact socket components and sealing socket components alternately. Automated production of plug contact sockets is not possible due to design constraints. The known solution is additionally overstressed with consideration of the process-induced shape and position tolerance of its individual components and, therefore, non-uniform forces may act on a real electrode plug fitted into such a plug contact socket and could consequently lead to malfunctions. It has also proven to be disadvantageous with such a known solution that the occupied installation space is comparatively bulky and does not allow any further volume reduction. The seal between the modularly constructed metal-conductive contact socket components and the intermediate electrically insulating sealing socket components additionally appears to be problematic.
An object is therefore to create a plug contact socket for a terminal housing that avoids the above disadvantages and, in particular, can be produced in a simple manner in terms of the equipment involved and, therefore, cost effectively. The plug contact socket should also conform to the above-specified standards.
The present invention is directed toward overcoming one or more of the above-identified problems.